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* [PATCH v51 02/10] Rename cluster.c/h -> repack.c/h
@ 2026-03-31 16:55 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-03-31 16:55 UTC (permalink / raw)
---
src/backend/commands/Makefile | 2 +-
src/backend/commands/matview.c | 2 +-
src/backend/commands/meson.build | 2 +-
src/backend/commands/{cluster.c => repack.c} | 6 +++---
src/backend/commands/tablecmds.c | 2 +-
src/backend/commands/vacuum.c | 6 +++---
src/backend/storage/ipc/procsignal.c | 1 +
src/backend/tcop/postgres.c | 1 +
src/backend/tcop/utility.c | 2 +-
src/include/commands/{cluster.h => repack.h} | 12 ++++++------
10 files changed, 19 insertions(+), 17 deletions(-)
rename src/backend/commands/{cluster.c => repack.c} (99%)
rename src/include/commands/{cluster.h => repack.h} (90%)
diff --git a/src/backend/commands/Makefile b/src/backend/commands/Makefile
index c10fdba2bbb..fe1bba3a9b9 100644
--- a/src/backend/commands/Makefile
+++ b/src/backend/commands/Makefile
@@ -18,7 +18,6 @@ OBJS = \
amcmds.o \
analyze.o \
async.o \
- cluster.o \
collationcmds.o \
comment.o \
constraint.o \
@@ -51,6 +50,7 @@ OBJS = \
proclang.o \
propgraphcmds.o \
publicationcmds.o \
+ repack.o \
schemacmds.o \
seclabel.o \
sequence.o \
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index d3be8939011..5db4fe75dce 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -24,8 +24,8 @@
#include "catalog/namespace.h"
#include "catalog/pg_am.h"
#include "catalog/pg_opclass.h"
-#include "commands/cluster.h"
#include "commands/matview.h"
+#include "commands/repack.h"
#include "commands/tablecmds.h"
#include "commands/tablespace.h"
#include "executor/executor.h"
diff --git a/src/backend/commands/meson.build b/src/backend/commands/meson.build
index 90c7e37a429..f624aae74af 100644
--- a/src/backend/commands/meson.build
+++ b/src/backend/commands/meson.build
@@ -6,7 +6,6 @@ backend_sources += files(
'amcmds.c',
'analyze.c',
'async.c',
- 'cluster.c',
'collationcmds.c',
'comment.c',
'constraint.c',
@@ -39,6 +38,7 @@ backend_sources += files(
'proclang.c',
'propgraphcmds.c',
'publicationcmds.c',
+ 'repack.c',
'schemacmds.c',
'seclabel.c',
'sequence.c',
diff --git a/src/backend/commands/cluster.c b/src/backend/commands/repack.c
similarity index 99%
rename from src/backend/commands/cluster.c
rename to src/backend/commands/repack.c
index f241e18b153..20f0a572236 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/repack.c
@@ -1,6 +1,6 @@
/*-------------------------------------------------------------------------
*
- * cluster.c
+ * repack.c
* REPACK a table; formerly known as CLUSTER. VACUUM FULL also uses
* parts of this code.
*
@@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
- * src/backend/commands/cluster.c
+ * src/backend/commands/repack.c
*
*-------------------------------------------------------------------------
*/
@@ -33,9 +33,9 @@
#include "catalog/pg_am.h"
#include "catalog/pg_inherits.h"
#include "catalog/toasting.h"
-#include "commands/cluster.h"
#include "commands/defrem.h"
#include "commands/progress.h"
+#include "commands/repack.h"
#include "commands/tablecmds.h"
#include "commands/vacuum.h"
#include "miscadmin.h"
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 0ce2e81f9c2..e2882a50b3b 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -57,10 +57,10 @@
#include "catalog/storage.h"
#include "catalog/storage_xlog.h"
#include "catalog/toasting.h"
-#include "commands/cluster.h"
#include "commands/comment.h"
#include "commands/defrem.h"
#include "commands/event_trigger.h"
+#include "commands/repack.h"
#include "commands/sequence.h"
#include "commands/tablecmds.h"
#include "commands/tablespace.h"
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index 0ed363d1c85..b179b62b5c8 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -9,7 +9,7 @@
*
* VACUUM for heap AM is implemented in vacuumlazy.c, parallel vacuum in
* vacuumparallel.c, ANALYZE in analyze.c, and VACUUM FULL is a variant of
- * CLUSTER, handled in cluster.c.
+ * REPACK, handled in repack.c.
*
*
* Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
@@ -38,9 +38,9 @@
#include "catalog/pg_database.h"
#include "catalog/pg_inherits.h"
#include "commands/async.h"
-#include "commands/cluster.h"
#include "commands/defrem.h"
#include "commands/progress.h"
+#include "commands/repack.h"
#include "commands/vacuum.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
@@ -2293,7 +2293,7 @@ vacuum_rel(Oid relid, RangeVar *relation, VacuumParams params,
if ((params.options & VACOPT_VERBOSE) != 0)
cluster_params.options |= CLUOPT_VERBOSE;
- /* VACUUM FULL is a variant of REPACK; see cluster.c */
+ /* VACUUM FULL is a variant of REPACK; see repack.c */
cluster_rel(REPACK_COMMAND_VACUUMFULL, rel, InvalidOid,
&cluster_params);
/* cluster_rel closes the relation, but keeps lock */
diff --git a/src/backend/storage/ipc/procsignal.c b/src/backend/storage/ipc/procsignal.c
index 7e017c8d53b..7cef6e43661 100644
--- a/src/backend/storage/ipc/procsignal.c
+++ b/src/backend/storage/ipc/procsignal.c
@@ -19,6 +19,7 @@
#include "access/parallel.h"
#include "commands/async.h"
+#include "commands/repack.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "port/pg_bitutils.h"
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 10be60011ad..9fbaa5c00f0 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -39,6 +39,7 @@
#include "commands/event_trigger.h"
#include "commands/explain_state.h"
#include "commands/prepare.h"
+#include "commands/repack.h"
#include "common/pg_prng.h"
#include "jit/jit.h"
#include "libpq/libpq.h"
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index 2b609bfc824..5f8c766c4be 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -26,7 +26,6 @@
#include "catalog/toasting.h"
#include "commands/alter.h"
#include "commands/async.h"
-#include "commands/cluster.h"
#include "commands/collationcmds.h"
#include "commands/comment.h"
#include "commands/conversioncmds.h"
@@ -46,6 +45,7 @@
#include "commands/proclang.h"
#include "commands/propgraphcmds.h"
#include "commands/publicationcmds.h"
+#include "commands/repack.h"
#include "commands/schemacmds.h"
#include "commands/seclabel.h"
#include "commands/sequence.h"
diff --git a/src/include/commands/cluster.h b/src/include/commands/repack.h
similarity index 90%
rename from src/include/commands/cluster.h
rename to src/include/commands/repack.h
index d6b62c747e8..85061158b0c 100644
--- a/src/include/commands/cluster.h
+++ b/src/include/commands/repack.h
@@ -1,17 +1,17 @@
/*-------------------------------------------------------------------------
*
- * cluster.h
- * header file for postgres cluster command stuff
+ * repack.h
+ * header file for the REPACK command
*
* Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
* Portions Copyright (c) 1994-5, Regents of the University of California
*
- * src/include/commands/cluster.h
+ * src/include/commands/repack.h
*
*-------------------------------------------------------------------------
*/
-#ifndef CLUSTER_H
-#define CLUSTER_H
+#ifndef REPACK_H
+#define REPACK_H
#include "nodes/parsenodes.h"
#include "parser/parse_node.h"
@@ -52,4 +52,4 @@ extern void finish_heap_swap(Oid OIDOldHeap, Oid OIDNewHeap,
MultiXactId cutoffMulti,
char newrelpersistence);
-#endif /* CLUSTER_H */
+#endif /* REPACK_H */
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0003-Add-CONCURRENTLY-option-to-REPACK-command.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
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^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v54 5/5] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d1be6c60e88..ec3a2cd441d 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3382,7 +3382,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--cdhh4t7ukb6tnjoq--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v52 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--gp2pyozrd5pweboh
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v52-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v53 7/7] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 86 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 ++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 117 insertions(+), 63 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d3fea738ca3..a90d163e416 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 92759f33969..6ba86384312 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index c85166ba849..39cbb0252f4 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -223,7 +223,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -232,8 +232,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -244,6 +244,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index dc46a372ead..06efcaa60b2 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -308,6 +308,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -328,6 +329,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -344,7 +346,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 9533515a63b..47679161b67 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -188,14 +190,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +211,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +225,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +375,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +383,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +436,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +453,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -454,7 +465,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -547,7 +559,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +587,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1655,17 +1668,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2216,7 +2236,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2244,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2349,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2450,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..9d7d675fa96 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1240,7 +1240,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1309,6 +1309,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1466,7 +1467,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index a315c4ab8ab..bf82b8f6048 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2071,6 +2071,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6d0337853e0..fb75990609e 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..489af7d8d6c 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -377,7 +378,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qr3jlalmmcpkiodg--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v51 09/10] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 80 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 3 +-
12 files changed, 93 insertions(+), 48 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 422ba304982..a67dd6b9eb1 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d4c1f0e7652..d932d526235 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3381,7 +3381,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..28c89c5e10d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..2c6c6773ad2 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -189,14 +191,15 @@ static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
Size
ReplicationSlotsShmemSize(void)
{
+ int totalslots = max_replication_slots + max_repack_replication_slots;
Size size = 0;
- if (max_replication_slots == 0)
+ if (totalslots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(totalslots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +212,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +226,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +376,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +384,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +437,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +454,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -455,7 +466,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -548,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +588,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,10 +1676,12 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* XXX we should be able to check exactly which type of slot we need */
+ if (max_replication_slots + max_repack_replication_slots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errmsg("replication slots can only be used if \"%s\" > 0 or \"%s\" > 0",
+ "max_replication_slots", "max_repack_replication_slots")));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2224,7 +2239,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2247,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2352,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2453,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2883,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2925,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..78dd3c4ea66 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fc0900efe5f..857be159f5c 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index c8194c27aa7..9c3c5d16361 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..c316a01a807 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,6 +324,7 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
@@ -334,7 +335,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--r2slln3zpmilwu22
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v51-0010-CheckLogicalDecodingRequirements-be-specific-abo.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v56 2/3] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 2 +-
src/backend/commands/repack_worker.c | 7 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/logical.c | 8 +-
.../replication/logical/logicalfuncs.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 84 ++++++++++++-------
src/backend/replication/slotfuncs.c | 19 +++--
src/backend/replication/walsender.c | 9 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/logical.h | 3 +-
src/include/replication/slot.h | 5 +-
15 files changed, 116 insertions(+), 62 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3324d2d3c49..3435732646e 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4639,6 +4639,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index e993dfb3108..c532a39ee07 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 17b639b3b44..5e97fcf3818 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3357,7 +3357,7 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 94d034970b5..ea330310e27 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -212,7 +212,7 @@ repack_setup_logical_decoding(Oid relid)
* Make sure we can use logical decoding.
*/
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(true);
/*
* A single backend should not execute multiple REPACK commands at a time,
@@ -221,8 +221,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
@@ -233,6 +233,7 @@ repack_setup_logical_decoding(Oid relid)
ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
NIL,
true,
+ true,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 9e75a3e04ee..7adf4dbe0d1 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 8ceaf64d164..d8e02c53558 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -108,9 +108,9 @@ static void LoadOutputPlugin(OutputPluginCallbacks *callbacks, const char *plugi
* decoding.
*/
void
-CheckLogicalDecodingRequirements(void)
+CheckLogicalDecodingRequirements(bool repack)
{
- CheckSlotRequirements();
+ CheckSlotRequirements(repack);
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
@@ -304,6 +304,7 @@ StartupDecodingContext(List *output_plugin_options,
* output_plugin_options -- contains options passed to the output plugin
* need_full_snapshot -- if true, must obtain a snapshot able to read all
* tables; if false, one that can read only catalogs is acceptable.
+ * for_repack -- if true, we're going to be decoding for REPACK.
* restart_lsn -- if given as invalid, it's this routine's responsibility to
* mark WAL as reserved by setting a convenient restart_lsn for the slot.
* Otherwise, we set for decoding to start from the given LSN without
@@ -324,6 +325,7 @@ LogicalDecodingContext *
CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
@@ -340,7 +342,7 @@ CreateInitDecodingContext(const char *plugin,
* On a standby, this check is also required while creating the slot.
* Check the comments in the function.
*/
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(for_repack);
/* shorter lines... */
slot = MyReplicationSlot;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 9760818941d..512013b0ef0 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -115,7 +115,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
if (PG_ARGISNULL(0))
ereport(ERROR,
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index 8b53bd3ac7f..ae900f13467 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -434,7 +434,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -823,6 +823,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1707,7 +1708,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a1f37e59dbc..e6722fc0212 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -160,6 +160,8 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -199,12 +201,13 @@ ReplicationSlotsShmemRequest(void *arg)
{
Size size;
- if (max_replication_slots == 0)
+ if (max_replication_slots + max_repack_replication_slots == 0)
return;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(max_replication_slots + max_repack_replication_slots,
+ sizeof(ReplicationSlot)));
ShmemRequestStruct(.name = "ReplicationSlot Ctl",
.size = size,
.ptr = (void **) &ReplicationSlotCtl,
@@ -217,7 +220,7 @@ ReplicationSlotsShmemRequest(void *arg)
static void
ReplicationSlotsShmemInit(void *arg)
{
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -366,6 +369,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -373,10 +377,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -425,12 +430,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = !repack ? 0 : max_replication_slots;
+ endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -438,7 +447,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -448,7 +459,8 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("all replication slots are in use"),
- errhint("Free one or increase \"max_replication_slots\".")));
+ errhint("Free one or increase \"%s\".",
+ repack ? "max_repack_replication_slots" : "max_replication_slots")));
/*
* Since this slot is not in use, nobody should be looking at any part of
@@ -541,7 +553,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -569,7 +581,8 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots +
+ (max_replication_slots + max_repack_replication_slots));
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -863,7 +876,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1245,7 +1258,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1300,7 +1313,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1367,12 +1380,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1447,11 +1460,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
@@ -1508,13 +1521,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1611,11 +1624,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1649,17 +1662,24 @@ CheckLogicalSlotExists(void)
* slots.
*/
void
-CheckSlotRequirements(void)
+CheckSlotRequirements(bool repack)
{
/*
* NB: Adding a new requirement likely means that RestoreSlotFromDisk()
* needs the same check.
*/
- if (max_replication_slots == 0)
+ if (!repack && max_replication_slots == 0)
ereport(ERROR,
- (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
- errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots can only be used if \"%s\" > 0",
+ "max_replication_slots"));
+
+ if (repack && max_repack_replication_slots == 0)
+ ereport(ERROR,
+ errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("REPACK can only be used if \"%s\" > 0",
+ "max_repack_replication_slots"));
if (wal_level < WAL_LEVEL_REPLICA)
ereport(ERROR,
@@ -2210,7 +2230,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (max_replication_slots == 0 && max_repack_replication_slots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2218,7 +2238,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2323,7 +2343,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2424,7 +2444,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (max_replication_slots + max_repack_replication_slots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..16fbd383735 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -90,7 +90,7 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
create_physical_replication_slot(NameStr(*name),
immediately_reserve,
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -164,6 +164,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ctx = CreateInitDecodingContext(plugin, NIL,
false, /* just catalogs is OK */
+ false, /* not repack */
restart_lsn,
XL_ROUTINE(.page_read = read_local_xlog_page,
.segment_open = wal_segment_open,
@@ -203,7 +204,7 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
create_logical_replication_slot(NameStr(*name),
NameStr(*plugin),
@@ -240,7 +241,7 @@ pg_drop_replication_slot(PG_FUNCTION_ARGS)
CheckSlotPermissions();
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
ReplicationSlotDrop(NameStr(*name), true);
@@ -270,7 +271,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < max_replication_slots + max_repack_replication_slots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -648,9 +649,9 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
CheckSlotPermissions();
if (logical_slot)
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
else
- CheckSlotRequirements();
+ CheckSlotRequirements(false);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
@@ -665,7 +666,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index b4a2117a7f9..bad45adb004 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1241,7 +1241,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1261,7 +1261,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
/*
* Initially create persistent slot as ephemeral - that allows us to
@@ -1272,7 +1272,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
@@ -1330,6 +1330,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
Assert(IsLogicalDecodingEnabled());
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
+ false,
InvalidXLogRecPtr,
XL_ROUTINE(.page_read = logical_read_xlog_page,
.segment_open = WalSndSegmentOpen,
@@ -1487,7 +1488,7 @@ StartLogicalReplication(StartReplicationCmd *cmd)
QueryCompletion qc;
/* make sure that our requirements are still fulfilled */
- CheckLogicalDecodingRequirements();
+ CheckLogicalDecodingRequirements(false);
Assert(!MyReplicationSlot);
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index fcb6ab80583..632f3ba4989 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2079,6 +2079,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index e3e462f3efb..2e10eb4a36a 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index bc9d4ece672..bc075b16741 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -115,11 +115,12 @@ typedef struct LogicalDecodingContext
} LogicalDecodingContext;
-extern void CheckLogicalDecodingRequirements(void);
+extern void CheckLogicalDecodingRequirements(bool repack);
extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
List *output_plugin_options,
bool need_full_snapshot,
+ bool for_repack,
XLogRecPtr restart_lsn,
XLogReaderRoutine *xl_routine,
LogicalOutputPluginWriterPrepareWrite prepare_write,
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 1a3557de607..77c8d0975b6 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,13 +324,14 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
@@ -373,7 +374,7 @@ extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname
extern void StartupReplicationSlots(void);
extern void CheckPointReplicationSlots(bool is_shutdown);
-extern void CheckSlotRequirements(void);
+extern void CheckSlotRequirements(bool repack);
extern void CheckSlotPermissions(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
--
2.47.3
--qs77q6fpwolne4ds
Content-Type: text/x-diff; charset=utf-8
Content-Disposition: attachment;
filename="v56-0003-Error-out-any-process-that-would-block-at-REPACK.patch"
^ permalink raw reply [nested|flat] 331+ messages in thread
* [PATCH v50 8/8] Reserve replication slots specifically for REPACK
@ 2026-04-01 17:54 Álvaro Herrera <[email protected]>
0 siblings, 0 replies; 331+ messages in thread
From: Álvaro Herrera @ 2026-04-01 17:54 UTC (permalink / raw)
This allows REPACK to not interfere with other operations that use
replication slots. This eases configurability.
---
doc/src/sgml/config.sgml | 16 ++++
doc/src/sgml/ref/repack.sgml | 6 +-
src/backend/commands/repack.c | 3 +-
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 78 ++++++++++++-------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
12 files changed, 96 insertions(+), 46 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index fdb77df0fdb..a87626a01b6 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4638,6 +4638,22 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
</listitem>
</varlistentry>
+ <varlistentry id="guc-max-repack-replication-slots" xreflabel="max_repack_replication_slots">
+ <term><varname>max_repack_replication_slots</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>max_repack_replication_slots</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Specifies the maximum number of replication slots for use of
+ the <command>REPACK</command> command. The default is 5.
+ This parameter can only be set at server start.
+ </para>
+ </listitem>
+ </varlistentry>
+
+
<varlistentry id="guc-max-replication-slots" xreflabel="max_replication_slots">
<term><varname>max_replication_slots</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index bec18c44cc8..1424446ba7c 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -293,9 +293,9 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
<listitem>
<para>
- The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
- configuration parameter does not allow for creation of an additional
- replication slot.
+ The <link linkend="guc-max-repack-replication-slots"><varname>max_repack_replication_slots</varname></link>
+ configuration parameter does not allow for the creation of an
+ additional replication slot.
</para>
</listitem>
</itemizedlist>
diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index d6e446d582d..2fc30008f59 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3383,7 +3383,8 @@ start_repack_decoding_worker(Oid relid)
ereport(ERROR,
errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("out of background worker slots"),
- errhint("You might need to increase \"%s\".", "max_worker_processes"));
+ /* FIXME rename to max_repack_processes? */
+ errhint("You might need to increase \"%s\".", "max_repack_replication_slots"));
decoding_worker->seg = seg;
decoding_worker->error_mqh = mqh;
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index ff34e246469..610592a05b0 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -233,8 +233,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d553bd5dbff..49fb10df038 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -152,6 +152,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 5; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -191,12 +194,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -209,7 +214,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -223,7 +228,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -373,6 +378,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -380,10 +386,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -432,12 +439,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -445,7 +456,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -548,7 +561,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -576,7 +589,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -870,7 +883,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1252,7 +1265,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1307,7 +1320,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1374,12 +1387,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1454,11 +1467,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1515,13 +1528,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1618,11 +1631,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1663,7 +1676,11 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /*
+ * FIXME how to relax this for repack in a way that doesn't mess
+ * everything up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2224,7 +2241,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2232,7 +2249,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2337,7 +2354,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2438,7 +2455,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2868,7 +2885,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2910,6 +2927,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 2bb3f34dc6d..75ef3419a15 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index e556b8844d8..8eb251659b0 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '5',
+ min => '0',
+ max => 'MAX_BACKENDS',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 2c5e98d1d4d..9e9a390a01b 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 5 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--brnevsqjnuzpyok4--
^ permalink raw reply [nested|flat] 331+ messages in thread
end of thread, other threads:[~2026-04-01 17:54 UTC | newest]
Thread overview: 331+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2026-03-31 16:55 [PATCH v51 02/10] Rename cluster.c/h -> repack.c/h Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v54 5/5] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v52 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v53 7/7] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v51 09/10] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v56 2/3] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
2026-04-01 17:54 [PATCH v50 8/8] Reserve replication slots specifically for REPACK Álvaro Herrera <[email protected]>
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